[Effects of summer pruning on the vegetative and productive behaviour of vinegrape (Vitis vinifera L.)]

English. The effects of summer pruning applied about 1, 7 or 11 weeks after anthesis, were studied on "Albana" and on "Sangiovese" grape cvs., respectively "Duplex" and "G.D.C." trained. During two years, pruning was performed, topping the hanging shoots and measuring the leaf area retained and removed. After pruning the berry growth and the ripening were followed; at harvest the leaf area replacement was recorded. As compared to the unpruned vines, the shoot topping shortly after anthesis increased berry growth and acidity accumulation during the period I (cell division); during period III (cell enlargment), the berry growth was also greater, the soluble solids accumulation was enhanced and the total acidity decreased more rapidly. In contrast the shoot topping 7 weeks after anthesis (end of period II) decreased berry growth, soluble solids accumulation and acidity degradation. Similar, but lesser, effects were recorded in vines pruned II weeks after anthesis (middle of period III). In conclusion, topping on period I enhanced ripening because the early growth of laterals replaced the mature leaf area in the period III. On the contrary, topping on period II or on period III delayed ripening for the removal of mature leaves and for the competitive effects of young laterals on clusters.

Italian. Sono stati studiati gli effetti della potatura verde attuata 1, 7 o 11 settimane dopo la piena fioritura sulle cultivar "Albana" e "Sangiovese" rispettivamente allevate a "Duplex" e a "G.D.C.". Per due anni la potatura venne effettuata cimando i germogli e misurando l'area fogliare rimasta e quella asportata. Dopo la potatura venne seguita la crescita e la maturazione degli acini. Alla vendemmia venne nuovamente misurata l'area fogliare. Rispetto alle viti non cimate, la cimatura effettuata subito dopo la piena fioritura aumento la crescita degli acini e l'accumulo dell'acidita durante il I periodo (moltiplicazione cellulare); per tutto il III periodo (distensione cellulare) la crescita degli acini si mantenne piu veloce, l'accumulo degli zuccheri venne accelerato e l'acidita diminui piu rapidamente. Al contrario, la cimatura a 7 settimane dopo la piena fioritura (fine del II periodo) diminui la crescita degli acini, l'accumulo degli zuccheri e la degradazione dell'acidita. Effetti simili, ma meno marcati furono ottenuti nelle viti cimate II settimane dopo la fioritura (circa a metta del III periodo).